Time delay mercury switch



July 2, 1940. P. L. SPEIQCER 2,206,436

TIME DELAY MERCURY SWITCH Filed June 29, 1938 Pergyl. Spa/ 26e,

Patented July 2, 1940.

UNITED/STATES TIME DELAY MEactmYjswrrcn Percy L. Spencer, West Newton, Masa, assignor to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application June 29, 1938,, Serial No. 218,445

9 Claims.

This invention relates to a mercury switch. and more particularly to a switch of this kind in which a time delay is introduced into the making or breaking of contact therein.

An object of my invention is to produce a mercury switch in which a body of mercury flows between two sections of a tube in order to make and break a circuit and in which the passage of said body of mercury is delayed in one direction and unimpeded in the other, so as to produce delayed action in one position of the switch and an immediate action in the other position of said switch.

This operation contemplates the production of two types of switches, namely a delay circuitmaking, quick circuit-breaking switch and a delay circuit-breaking, quick circuit-making switch.

Another object of this invention is to produce switches of the foregoing type with a minimum of structural complexity and a maximum of reliability.

The foregoing and other objects of 'my invention will be best understood from the following description of exempliflcations thereof, reference being had to the accompanying drawing, wherein- Fig. 1 is a perspective view of a delay circuitmaking, quick circuit-breaking switch embodyingmy invention;

Fig.2 is a cross-section taken along line 2--2 of Fig. 1; and

Fig. 3 is a perspective view of a delay circuitbreaking, quick circuit-making switch also embodying my invention.

The switch shown in Fig. 1 comprises a glass envelope 1 with two conductors 2 and 3 sealed through a press 4 at one end thereof. The conductor 3 is insulated by being coated with a glass covering 5 along the substantial portion of its length within the envelope I. The conductor 3 carries a contact-making and breaking terminal 6' at its outer end. The envelope I contains a body of mercury l and is filled with an inertgas, preferably hydrogen, at a pressure somewhat below atmospheric pressure.

When the body of mercury 1 contacts both the conductor 2. and the terminal 6, a circuit is established between the conductors 2 and 3, and thus the switch is in its closed position. When, however, the body of mercury leaves the terminal 6, the switch is in its opened position.

the glass envelope. The baille plate 8 is provided at one side thereof with a circular opening 9 intercepting one edge of the bafile plate, leaving one side of the baflie plate cut away. A metal ball I0, preferably of steel, is provided so as to close the circular opening 9 in one position of the switch. The ball I0 is made somewhat larger in diameter than the opening 9. The

baille plate 8 is also cut away to a limited extent at'one side of the opening in its edge, as indicated at II. When the metal ball I0 closes the circular opening 9, a closure is effected only to the extent as indicated by the dotted line in the lower portion of Fig. 2. Thus the cut-away portion II leaves a small aperture through which the mercury within the switch can pass slowly, as will be described below. In order to keep the metal ball I0 within the proper limits of motion, a retaining frame I2 is welded to that side of the baille plate 8 at which the metal ball I0 is located. The retaining frame I2 is of suflicient extent to permit the metal ball ID to roll away from the opening 9 and leave it substantially unobstructed for the passage of mercury therethrough when the switch is tilted substantially to a position as shown in Fig. l. The conductors 2 and 3 extend through the press 4 to the exterior of the switch' envelope I. The conductors 2 and 3 may likewise be provided with external flexible leads I3 in order that the switch may be connected in whatever circuit it is desired to control.

The operation of the switch which I have described is substantially as follows. With the switch initially in the position as shown in Fig. 1, the body of mercury 'l is at the lower end thereof and the circuit between the conductor 2 and the terminal 6 is opened. As the switch envelope I is rotated in a clockwise direction, the metal ball III will roll into the position as indicated by the dotted lines in Fig. 1 so as to close the circular opening 9 to the extent as indicated by the dotted lines in the lower portion of Fig. 2. Not only will this motion of the ball Ill be affected by the force of gravity acting on the wall itself but the weight of the body of mercury l behind the ball II) will push said ball firmly into position in said opening 9. I have found that the mercury will not flow through openings which are less than a predetermined size. This permits considerable latitude in the clearance between the edges of the baflle plate 8 and the inner walls of the envelope I as well as the clearance between the edges of the opening 9 and the outer surface of the metal ball Ill. It is merely necessary that these clearances be reasonably close. The small opening at II, however, is of sufllcient size so that the mercury flows in a relatively small stream through said opening. The mercury flowing from one side of the battle disk to the other displaces the gas within the envelope. Therefore it is desirable to cut away the upper edge of the heme disk 8 at 8' so as to provide a gas vent, whereby the gas displaced may flow' freely from one side to the other of said bafile plate. The small stream of mercury gradually fills the upper end or the envelope I to the level indicated bythe dotted line adjacent the terminal 6. However, when the envelope in Fig 1 is rotated in the clockwise direction, this level is not reached until substantially all of the mercury i has flowed through the opening at Ii. Therefore, the circult is not closed until a predetermined time interval has elapsed after the actuation of the switch. The length of this time delay depends upon the specific dimensions of the envelope, the bafile disk 8, and the mercury i.

If it is desired to open the switch, the envelope i is rotated in a counter-clockwise direction back to the position indicated in Fig. l. Thereupon the'ball II: rolls to the end of the frame l2, leav ing the opening 9 unobstructed. It will be noted, furthermore, that the lower glass wall of the envelope I through the bottom of the opening 9 is also unobstructed. This permits the body of' mercury I to flow freely along said glass surface through the opening 9 to its position in the lower end of the envelope. Under these conditions the mercury I leaves the terminal 6 substantially instantaneously upon the actuation of the switch to its open position,

From the foregoing it will be seen that the specific form of the switch illustrated in Fig. 1 introduces a time delay in the closing of the circuit while the breaking of the circuit takes place substantially instantaneously.

If a switch is desired in which a time delay is introduced in the breaking of the circuit, it is merely necessary to support the metal ball on the opposite side of the bafiie disk. Such an arrangement is shown in Fig. 3. The switch inFig. 3 comprises a glass envelope it having two conductors I Send I6 sealed through a glass press H at one end thereof. The conductor I5 is insulated by a glass covering I8 and provided with a contact-making terminal it, as described in connection with conductor 3 of Fig. l. The conductor l6 supports a baffle plate 20.provided with a circular opening 2|, one edge of which is cut away at 22, as described in connection with the baffle plate 8 of Fig. 1. A metal ball 23 is located on the same side of the bafiie plate 28 as the contact-making terminal I9, and is adapted to substantially close the opening 2| in one position of actuation of the'switch. A retaining frame 24 is likewise welded to the same side of the baille disk 20, and permits a limited motion of the ball 23 so that it may close and open the circular opening 2|. The envelope I4 is provided with a body of mercury and a gas filling, as described in connection with Fig. 1.

When the envelope I4 is substantially in the position as indicated in Fig. 3, the body of mercury reaches substantially the level shown by the horizontal dotted lines. In this position the cir cuit between the terminal I9 and the conductor I8 is completed. As the envelope M is rotated in a counter-clockwise direction, the metal ball 23 closes the opening 2| and causes the mercury to flow in asmaller stream through the cut-away portion at 22. Thus the mercury flows slowly from the right-hand end of the envelope I4 to the left-hand end thereof. Due to this delayed flow of mercury, the level of the mercury does not fall accuse below the contact-making terminal I9 until a predetermined time interval has elapsed. This time'interval likewise depends upon the dimensions of the various parts of the switch. when the flow of mercury stops, it attains a level substantlally as indicated by the dotted line at the left-hand end of Fig. 3.

If it is now desired to re-close the switch, the envelope M is rotated in a clockwise direction back to the position shown in Fig. 3. The ball 23 rolls away from the opening 2!, and therefore the flow of mercury through said opening is substantially unimpeded, whereupon the original level is reached without appreciable lapse of time. Therefore, upon this actuation of the switch, the circuit is re-c losed substantially instantaneously. 'Of course it is to be understood that this invention is not limited to the particular details of construction as described above as many equivalents will suggest themselves to those skilled in the art. For example, instead of forming the restricted aperture adjacent one edge of the large circular opening, a separate restricted aperture could be provided in the face of the baiiie plate. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of the invention.

What is claimed is:

l. A time delay switch comprising an envelope, a seal at one end of said envelope, a separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a body of conducting liquid in, said envelope adapted to move into electrical contact with both of said conductors the closed position of said switch, an opening in said partition member, a closure member located in one of said chambers and adapted to move toward said partition memher to close said opening and away from said partztion to uncover said opening, and an aperture of restricted size in said partition member through which a delayed flow of said liquid may occur when said opening is closed by said closure member.

2. A time delay switch comprising an envelope,

a seal at one end of said envelope, a. separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a. body of conducting liquid in said envelope adapted to move into electrical contact with both of said conductors in the closed position of said switch, an opening in said partition member, a closure member located in one of said chambers and adapted to move toward said partition memher to close said opening and away from said partition to uncover said opening, guiding means for guiding said closure member into closing engagement with said opening, and an aperture of restricted size in said partition member through which a. delayed flow of said liquid may occur Itgrehen said opening is closed by said closure mem- 3. A time delay switch comprising an envelope, a partition member comprising a metal plate extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through a wall of said envelope and extending into one of said chambers, said metal plate being electrically con- .1

nected to and supported by one or said conductors, a body of conducting liquid in said envelope adapted to move into electrical contact with both 01 said conductors in the closed position of said switch, an opening in said partition member, a metal closure member located in one of said chambers and adapted to move toward said partition member to close said opening and away from said partition to uncover said opening, and an aperture of restricted size in said partition member through which a delayed flow of said liquid may occur when said opening is closed by said closure member.

4. A time delay switch comprising an envelope, a seal at one end of said envelope, a separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a body of conducting liquid in said envelope adapted to move into electrical contact with both of said conductors in the closed position of said switch, an opening in said partition A member, a closure member located in the same chamber as said conductors and adapted to move toward said partition member to close said opening and away from said partition to uncover said opening, and an aperture of restricted size in said partition member through which a delayed flow of said liquid may occur when said opening is closed by said closure member.

5. A time delay switch comprising an envelope, 9. seal at one end of said envelope, a separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a body of conducting liquid in said envelope adapted to move into electrical contact with both of .said conductors in the closed position of said switch, an opening in said partition member, a closure member located in the other of said chambers and adapted to move toward said partition member to close said opening and away from said partition to uncover said opening, and an aperture of restricted size in said partition member through which a delayed flow of said liquid may occur when said opening is closed by said closure member.

6. A time delay switch comprising an envelope, a seal at one end of said envelope, 2. separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a body of conducting liquid in said envelope adapted to move into electrical contact with both of said conductors in the closed position of said switch, an opening in said partition member intercepting the edge of said partition member to provide an uninterrupted path along one side wall of said envelope for the flow of said liquid in one direction, a closure member located in one of said chambers and adapted to move toward said partition member to close said opening and away from said partition to uncover said opening, andan aperture of restricted size in said partition member through which a delayed flow of said liquid may occur when said ope ing is closed by said closure member.

7. A time delay switch comprising an envelope, a seal at one end of said envelope, a separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a body of conducting liquid in said envelope adapted to move into electrical contact with both of said conductors in the closed position oi said switch, an opening in said partition member, a closure member located in one of said chambers and adapted to move toward said partition member to close said opening and away from said partition to uncover said opening, one edge of said opening being cut away to provide an aperture of restricted size in said partition ember through which a delayed flow of said liquid may occur when said opening is closed by said closure member, the flow of said liquid through said opening being substantially unimpeded when said opening is uncovered by said closure member.

8. A time delay switch comprising an envelope, a seal at one end of said envelope, a separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a body of conducting liquid in said envelope adapted to move into electrical contact with both of said conductors in the closed position of said switch, an opening in said partition member, a closure member located in one of said chambers and adapted to move toward said partition member to close said opening and away from said partition to uncover said opening, an aperture of restricted size in said partition member through which a delayed flow of said liquid may occur when said opening is closed by said closure member, an inert gas filling in said envelope, and a gas vent in the upper part of said partition member connecting both chambers through which gas, displaced by the flow of said liquid, may pass.

9. A time delay switch comprising an envelope, 9. seal at one end of said envelope, a separate partition member supported from said seal, extending transversely across said envelope and dividing the interior of said envelope into two chambers, two conductors sealed through said seal and extending into one of said chambers, a body of conducting liquid in said envelope adapted to move into electrical contact with both of said conductors in the closed position of said switch, an opening in said partition member, a closure member located in one oi said chambers and adapted to move toward said partition member to close said opening and away from said partition to uncover said opening, guiding means supported by said partition member for guiding said closure member into closing engagement with said opening, and an aperture of restricted size in said partition member through which a delayed flow of said liquid may occur when said opening is closed by said closure member.

PERCY L. SPENCER. 

